I know this has been recently discussed, but damned if I can find the thread by searching. To avoid a late night affair, I'm planning to mash and collect wort one night, cover it, and do my boil the next day some time (probably morning).

My recollection is that someone in one of the previous threads said you should really bring your wort up to 170F to make sure you've killed off the lactobacillus. Do I have that right?

i would not recommend lagging from mash to boil. this will give ample opportunity for lots of bad things to happen. infections, animal and bug takeover, i mean, lots of bad things can happen. if you dont have time to do your boil, then dont do the mash. once you start, you gotta finish.

Yes - I've thought about this too.
I think the ideal way if you MUST leave the full boil until the next day would be to Mash, sparge, then bring it up to a boil in a covered container - (do not open the lid), turn off the flames and go to bed. Next day start the boil in earnest. Bringing the wort up to boil in an enclosed vessle will 99.9% prevent contamination by microorganisms (but yes, if you have roaches or rats around they will come to investigate).

There's no reason why you couldn't do this if your wort was brought to 170F and stored in a sanitized vessel overnight, preferably chilled. When the wort is boiled the next day, any bugs that had decided to snack on your wort would be killed.

I recently did this involuntarily. I was mashing and work called so I went in and ended up leaving my mash for 9 hours and it dropped from 150 to 120.

I was low on propane and had barley enough to sparge then put it in the fridge over night. Boiled next day and fermented and it went to 1.000

Im probably just going to dump it, has some sourness to it.

Yeah, this is a different scenario and seems one that has much more potential for problems, including the sourness and overattenuation you experienced. If I do it, I'll be completing the mash and sparge, brining up to temp to denature enzymes and kill lacto and then store overnight.